parse JSON, iOS, Swift4 - ios

Question

I am trying to parse some json but seem to be getting nil in the outputs.
I am not sure where I am going wrong and could use some help trying to figure this out.
struct albumInfo: Decodable {
var name: String?
var artist: String?
var url: String?
var playcount: String?
var listeners: String?
var releasedate: String?
var summary: String?
}
class SearchVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
Choice = "album"
Album = "Believe"
Artist = "Cher"
let tryURL = "\(BASE_URL)\(Choice!).getinfo&api_key=\(API_KEY)&artist=\(Artist!)&album=\(Album!)&format=json"
print(tryURL)
guard let url = URL(string: tryURL) else { return }
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data else { return }
do {
let albumDescription = try JSONDecoder().decode(albumInfo.self, from: data)
print(albumDescription.artist)
}catch let jsonErr {
print("Error seroalizing json", jsonErr)
}
}.resume()
}
Here is the data as shown with the tryUrl.

Answer 1

First of all please conform to the naming convention that struct names start with a capital letter.
There are two major issues:
The root object is a dictionary with one key album containing the dictionary with keys name, listeners etc.
The key summary is in another dictionary for key wiki.
The structure of the JSON is very easy to identify. The body within each pair of braces ({}) represents a separate struct.
Further there is no key releasedate so this struct member has to be declared as optional, all other members can be declared as non-optional and as constants (let). url can be declared as URL for free.
Change your structs to
struct Root : Decodable {
let album : AlbumInfo
}
struct AlbumInfo: Decodable {
let name: String
let artist: String
let url: URL
let playcount: String
let listeners: String
let releasedate: String?
let wiki : Wiki
}
struct Wiki: Decodable {
let content: String
let published: String
let summary: String
}
and decode Root
let albumDescription = try JSONDecoder().decode(Root.self, from: data)
print(albumDescription.album.artist)

Answer 2

The first key of your response is "album", you need to parse that first.

Answer 3

The classes do not correspond to json, I guess you should use the following approach (new classes implement your decode, encode protocol):
class JsonInfo {
var album : albumInfo
}
do {
let albumDescription = try JSONDecoder().decode(albumInfo.self, from: data)
print(albumDescription.album.artist)
}catch let jsonErr {
print("Error seroalizing json", jsonErr)
}